Question

A pharmacist must prepare 80 g of 8% w/w hydroquinone cream for a patient with hyperpigmentation disorder. How many grams of hydroquinone must she add a 5% w/w hydroquinone stock cream to complete the request?

Answer 1

Answer:

   80 g = 8%

   ? g = 5%

Among this if one amount was increases and then another amount increases at the same rate, so both are Directly proportional to each other.

Then 8/80 = 1/10 = 10

So 10 X 5 = 50 g

                    80 g = 8%

                    50 g = 5%

So finally 50 grams of hydroquinone must she add a 5% w/w hydroquinone stock cream to complete the request.